Lithium secondary batteries are largely used as power supplies in portable devices and the like. Diversification in the functions of portable devices and the like has led to the growth in power consumption. This has been prompting demands for an increase in the capacitance and improvement in the charge-discharge cycle characteristics of lithium secondary batteries. In a lithium secondary battery, usually, a lithium salt such as lithium cobaltate serves as a cathode active material and graphite and/or the like serve as an anode active material.
Capacitance can be increased by enhancing the electrode packing density of a carbonaceous material used in an anode. When an electrode packing density is enhanced using a conventional carbonaceous material, however, deformation and/or the like of the carbonaceous material may occur to lead to significant degradation of charge-discharge cycle characteristics.
Because of this, studies are conducted to improve a carbonaceous material itself for use in an anode so as to increase capacitance and improve charge-discharge cycle characteristics. For example, Patent Document 1 and Patent Document 2 describe composite graphite having a particular crystal structure. Patent Document 3 describes combined use of graphite having a particular crystal structure and a vapor grown carbon fiber having a particular crystal structure. Patent Document 4 describes a carbon composite material that is obtained by adhering an organic compound serving as a polymer raw material to carbonaceous particles such as graphite particles, polymerizing the organic compound, and then heating it at 1800 to 3300 deg C.    Patent Document 1: JP 2007-141677 A    Patent Document 2: WO 2007/072858 A    Patent Document 3: JP 2007-42620 A    Patent Document 4: JP 2005-158718 A